Centrifugal casting



Nov. 10, 1931.A I y B. LINDEMUTH 1,831,310

CNTRIFUGAL CASTING Filed March 30. 1927 GWW u Patented Nov. 10, 1931 LEWIS .'B. LINTDECMUTH, OF NEW YORK, N. Y.

CENTRIFUGAL CASTING Application led March 30, 1927. Serial No. 179,529.

y invention has relation to centrifugal castings and their manufacture, and has for its object to produce such a casting free from external or interior surface cracks, orboth,

with smooth surfaces free .from inclusions and oxidation.

lVith centrifugal castings, especially of ingots of special metals the losses due to inclusions and surface cracks are high. (I obviate these by making a smooth ingot, free of inclusions, that can at oncebe cut into billets for the finishing.,r rolls.

The inner surface of centrifugally cast in gots is customarily rough, due to impurities from the metal, oxidation and other sources.

These impurities have beendriven to the inner surface b v reason of being lighter than the metal of the casting, and by the centrifugal force during,Y the casting,r operation.

Such inclusions` for example withsteel, may be fused fire brick. silica, alumina, silicates and oxides of iron, silicates and oxides of manganese, and other substances incident to the manufactiuin,"Y or smeltinc,r operation, a remelting operation, a metal finishing operation. or parts of the containers or linings used in handling the molten metal.

My invention is not confined to the centrifugal casting of plicable to any other metal or alloy where smooth castings are the desideratum.

Centrifugal castings having smooth interiors require litt-le or no machining1 or grinding of their interior surfaces before rolling 'p to final shape. Then such castings are to be used directly without rollingr as pipes, bearings, bushings and the like, they require not so deep a finish: lo ing or truing cut thereby saving;r both material and labor.

Pipes so made have a smoother interior, offering less resistance to fluid flow. My invention is practiced as follows 5 The centrifugal mold is first set in rotationvand I place therein a temporary material, metal or alloy, heavier than the luseful n ietal of the casting to line the mold. Such heavier material, metal or alloy, necessarily D melting at a lower temperature than the useferrous metals, but is ap.

ful metal or its pouring temperature, and not vaporizing at such temperature.

The heavy metal may, for example, be lead or a lead alloy, and the useful metal a steel.

The heavy material, metal or alloy, may be charged cold, but I prefer to charge it molten.' When charged cold the heat of the useful metal (steel for example) will melt the substance or substances that are to form the mold lining. Molten lead may be poured into the rotating mold either first, or simultaneously with the molten iron or steel. This heavy metal under centrifugal action, whether introduced first or simultaneously I or last, covers the interior of the rapidly 155 rotating mold, and finds its way to and against the inner surface of the rotating mold v by reason of its greater weight and the cen-l trifugal force. y

ien operating with the heavier metal in a molten state'the useful metal, a steel, brass or bronze previously meltedis poured either after or simultaneously with the heavy metal. The casting' or ingot is then allowedto set or freeze while the rotation is maintained.

I remove the ingot or casting from the 'mold in the following manner: While the casting is still hot centrifugal motion is stopped and the heavy molten material or lmetal still liquid from the heat of the usefulv casting is tapped off, after which the casting` is removed, or the casting is allowed to cool and shrink and the composite ycasting of metal and moldlining material is then removed and the heavier lining material or metal subsequently removed for re-use, if desired. Conveniently the heavy metal or material is melted ofl".

The quantity of temporary exterior heavy metal coating, as lead or lead alloy. is usu- 9G ally small, about five percent by volume of the useful meta steel, bronze &c. However, where ingots are not in question and thin castings are/made. the heavy mold lining r may reach as much as fifty percent of the Q0* metal of the casting. p

I do not limit my invention to the use of any particular quantity of heavy mold lining metal or material, as the desideratum is to fully cover the interior surface of the mold and a larger or smaller quantity will do no harm.

In lieu of a metal I may use any other .f'fzeltable heavy substance satisfying the conditions under which a heavy lmetal or alloy is used, for example, a heavy slag, such as a slag containing about fifty percent of barium, which may be tapped from the cenas ingots.

This lining also acts, so to say. as a lubricant between the mold and useful metal casting during its contraction and cooling.

In coniunction with, or independently of the above described procedure I also smooth the interior of the centrifugal casting, and use inthe interior of the casting a protective coverin".r lighter than the metal of the cast- ,ing proper, which covering may or may not be Wholly or partly permanent.

Such internal protecting covering may be a slag-like substance or a metal. If a slag, I prefer an acid slag composed of sodium calcium and lead silicates, producing a coatingI resembling glass.

Inasmuch as the specific gravity of the inclusions average, with ferrous metals. a specic gravity of three, such a slag or glass is made up to`have a gravitv of say 3.50 to 4.00 and its quantity should be about 10% to 20% of the thickness of the useful metal being cast.

Such a slag may be formed directly in the casting in the-rnold bv introducing the slag forming materials. which become iiuid from the heat in the casting metal, or the slag may be first melted and then poured into the Y mold.

When there is no heavy molten mold lining used it is advantageous to irst pour into the mold the molten slag or the slag forming -materials and then pour into the mold the metal.

.This metal then passing through the slag and seeking the inner surface of the mold displaces the slag to the interior of the casting. The slag carries with it the impurities in the metal.

After the casting has cooled and shrunken it is removed from the mold with the covering of the inner surface of the casting adhering to it.

In some cases it is desirable to remove it, as with ingots. in others it is desirable to Ileave this covering as an internall coating of the casting, adhering toit. as with pines. In the latter case enamels may be used as the slag.

In the former case, i. e., with ingots, it is preferably a glass, and this I remove in any manner.

When a cylinder ingot having a slag lining cover is cut longitudinally into billets, the slag is nearly all removed during this sub-dividing operation.

I have found it convenient after drawing the casting with its adhering internal slag cover coating from the mold and still containing some of the casting heat to remove the internal slag coat by cracking it off with a spray of water, either as such or in the formv For example, after the casting has set, r

and While still hot I may introduce lead or lead alloy, cold or molten, which protects the interior of the casting from undue oxidation and floats the inclusions toward the interior surface of the mold. After the casting is drawn from the mold, this coating is melted o for re-use.

Or. I may,use aluminum, which may be charged cold or molten. When charged cold, the heat of the mold and the reaction of the aluminum with the oxide coating on the interior of the casting (which reaction is strongly exothermie) melts the aluminum and the adjacent surface of the still hot casting, carrying the inclusions to the center of the aluminum protecting coat, as Well as the slag that is formed during reaction with the oxide and inclusions.

The aluminum may also be introduced into the casting molten.

The covering materials may or may not have some solvent action on themetal of the casting, depending upon the relative composition of casting and covering material. All prevent oxidation of the casting metal during cooling.

Brass or bronze may also be used as a prohering to it. 1nwhich condition it may be rolled to enlarge its diameter While reducing with the mold,

' tacting ing its thickness, or drawn posite or clad metal article. v

When the lighter internal coating is completely taken olf the amount removed from the metal of the casting', as of a` ferrous metal, need be small, as its surface is clean and free from cracks a finishing cutis Loose molders sand may he used as a cover where prevention of too great oxidation of the .inner surface of the mold is the aim.

As illustrative of the invention the following diagrammatic drawings are appended, in which like parts are similarly designated.

Figure 1 is a diagrammatic cross section of an ingot mold with the ingot therein, and

F' ig. 2 is a front View of the same'.

In these drawings, whose sha-ft 2 directly or indirectly drives a gear 3 that meshes with a gear ring 4 onthe revoluble ingot mold 5 provided with la flange 6 at on end, which flange may be integral, and at its other end with a removable ring 7 held in place by bolts 8. is provided with a molten metaldischarge pipe 9 plugged with clay or otherwise stopped. The mold is mounted and rotates on the usual supporting rollers 10.

Beneath the pipe 9 is placed a receptacle 11 for the molten lead or slag.

The mold in this particular instance is shown to contain the mold lining a, the useful metal oringot metal b andthe internal coating c.

The mold is set in rotation by the motor, and the materialsV are supplied thereto in any order, as previously described.

After the casting b has set. the plug is wit-hdrawn from the is permitted to run into the receptacle 11, after which the ring 7 is taken off andthe casting drawn from the mold.

I prefer to use some sort of positive draw olf device for the mold lining` as the pipe 9, rather than allow the molten lining to spill out between the ring and mold end as the ring is being removed.

l. The art of making centrifugal castings, which comprises providing a mold duringr its rotation with casting metal and a molten temporary lining heavier lthan the casting metal to prevent the casting metal from conwith the mold, stopping the mold and removing the temporary7 lining and casting.

2. The art of makingcentrifugal castings, which comprises providing a mold during its rotation with casting metal and a molten temporary lining heavier than the casting metal to prevent the casting metal from contactallowing the liningto solidify on the casting, stopping the mold and thereafter simultaneously removing the temporary lining and cast-ing.

3. The art of making centrifugal castings,

to form a comnecessary.

and inclusions, so that only -the casting.

`ing metal to l is an electric motor The ring 7- pipe 9 and the mold lining which comprises -which comprises lining a centrifugal mold during its rotation with a molten temporary lining heavier than the metal of the casting, pouring the casting, allowing the lining and casting to harden andremoving them as a compound casting, -saidlining forming an exterior temporary protectingcoating for 4. The art of making centrifugal castings, which comprises providingrv a mold during its rotation With casting metal and a molten temporary lining of metal heavier than the castprevent the casting metal from contacting with the mold and to give to the casting a smooth surface free from shrinkage cracks during cooling, stopping the mold and removing the temporary lining and casting.

5: The art of making centrifugal castings, which comprises lining a centrifugal mold during its rotation with a molten temporary lining of metal heavier than the metal ofthe casting, pouring the casting,y allowing the lining and casting to harden and removing them as a compound casting.

6. The art of making centrifugal castings, which comprises lining a centrifugal mold during its rot-ation with a molten temporary lining heavier than'the metal of the casting, pouring the casting,allowing the tempora lining and casting to harden, removing them as a compound casting, and removing the mold lining from the exterior of the casting.

7". The art of making centrifugal castings, which comprises'providing amold during its rotation with a temporary molten lead lining and the metal and removing lead and casting.

8: The art of making centrifugal castings, which comprises providing a mold during its rotation with a molten lead lining and the metal to be cast, the lead preventing the metal to becast from contacting with the mold and producing a smooth exterior surface to the resulting casting substantially free from shrlnkage cracks stopping the mold and thereafter simultaneously removing lead and casting.

whlch comprises providing a mold during rotation with a molten .lead lining andthe to be cast, stopping the mold metal to be cast, stopping the mold and therc` after simultaneously removing the lead and casting, and removing the lead from the casting before further use'of the casting.

10. The art of making centrifugal castings, providing a mold during its rotation'with a molten lead lining and the K metal to be cast, stopping the mold and there.-

after simultaneously removing lead and casting, andvmelting the lead from the casting.

1'1. The art of making centrifugal castings, which comprises mold during its rotation with casting metal, a moltenl mold lining and a temporary cover for the interior of the casting centrifugally providing a centrifugal.

distributed over the inner surface of the casting.

12. The art of making centrifugal castings, which comprises providing a centrifugal mold while in a state of rotation With a heavy molten lining, a casting metal and a molten cover coating for the interior surface of the casting metal which is heavier than the in clusions in the casting metal.

13. The art of making centrifugal castings, which comprises providing a centrifugal mold While in a state of rotation with a neavy molten lining, a casting metal and a molten cover coating for the interior surface of the casting metal which is heavier than the inclusions in the casting metal, removing the composite casting from the mold, removing the mold lining from the casting and removing at least a portion of the cover coating.

14. The art of making centrifugal castings, Which comprises providing a mold while in a state of rotation With casting metal and a temporary protecting coating or layer for the inner surface of the casting.

15. The art of making centrifugal castings, which comprises providing a mold While in a state of rotation with casting metal and a molten temporary protecting coating or layer for the inner surface of the casting and `removing the coating before use of thecasti. The art of making centrifugal castings, Which comprises providing a mold While in a state of rotation with casting metal and a temporary protecting coating or layer for the interior surface of the casting that is lighter than the casting metal and removing the coating containing the inclusions.

17. The art of making centrifugal castings, which comprises providing a mold while in a state of rotation With casting metal and a temporary molten protecting coating or layer for the interior surface of the casting that is lighter than the casting metal and removing the coating containing the inclusions.

18. The art of making centrifugal castings, Which comprises providing a mold While in a state of rotation with casting metal and a protecting coating or layer for the inner surface of the casting and removing at least a part of this internal coating from the castin. The artof making centrifugal castings, which comprises providing a mold While in a state of rotation With a temporary slag and casting metal and removing the slag containing the inclusions.

r20. The art of making centrifugal castings,

which comprises providing a mold While in a' state of rotation with a temporary slag of less specific gravit-y than the metal but of greater specific gravity than the inclusions, and with casting metal and removing the slag containing the inclusions.

21. The art of makin centrifugal castings, which comprises provi ing a mold While in a state of. rotation with a temporary lead slag and casting metal and removing the slag containing the inclusions.-

22. The art of making centrifugal castings, Which comprises providing a mold While in a state of rotation with an acid lead slag and casting metal and removing the slag containing the inclusions.

28. The art of making centrifugal castings, which -comprises providing a mold While in a state of rotation with liquid metal and a slag of less gravity than the metal but of greater gravity than the metal inclusions, drawing the casting and removing the internal coating.

24. The art of making centrifugal' castings, which comprises providing a mold while in a state of rotation with liquid metal and a slag of less gravity than the metal but of greater gravity than the metal inclusions, drawing the casting and removing the internal coating by Water.

25. The art of making centrifugal castings, which comprises providing a mold While in a state of rotation with liquid metal and a slag of less gravity than the metal but of greater gravity than'the metal inclusions, dranfin the casting and removing the internal coating by water in the form of steam.

26.' The step in the making of smoothcentrifugal castings, which comprises pouring molten metal into a rotating mold, and thereafter pouring therein a metal lighter than the metal of the casting but heavier than the inclusions of the metal being cast.

27. The step in the making of smooth centrifugal castings, which comprises pouring molten metal into a rotating mold, and thereafter pouring therein a metal lighter than the metal of the casting but heavier than the in: clusions of the metal being cast, and removing at least a part of the lighter metal after the casting has cooled.

28. The art of making centrifugal castings, which comprises providing the mold While in a state of rotation with a slag in the nature of a lead glass and casting metal, said glass protecting the internal surface of the casting against oxidation and carrying theinclusions of the casting metal, and is readily removable.

In testimony that I claim the foregoing as my invention I have signed my name hereto. 1

LEWIS B. LINDEMUTH. 

